Once a running back’s nightmare, Gang Green’s front seven has become a haven for yards and touchdowns on the ground.

The Jets have allowed opposing rushers a whopping 4.9 yards per carry, fourth-worst in the NFL. They have given up eight touchdowns, second-worst in the NFL.

Yes, it’s been bad.

But coming off games in which Frank Gore and Arian Foster, respectively, ran all over the field, the Jets might have caught a break: Donald Brown is out.

Brown, the Colts’ starting running back, had knee surgery Tuesday and is expected to miss two to three weeks.

In his stead, the Colts will start Vick Ballard — a rookie out of Mississippi State taken in the fifth round of this year’s draft and a virtual unknown.

Jets LB Aaron Maybin said he had never heard of Ballard before this week. “They had Donald Brown, and there was a bunch of other guys,” Maybin said. Delone Carter and Mewelde Moore are also expected to get some work.

“You can put a guy in the backfield who runs a 5.5. If you don’t play good technique and get off blocks well and tackle well, he can run for 200 yards on you,” said Thomas. “I don’t care who it is."